Traffic staging control system

ABSTRACT

This is a system for regulating traffic flow by limiting the number of vehicles that can pass a given point on the roadway in a given interval of time. Basically, it provides a staging area in the roadway having a plurality of staging zones wherein each zone is provided with a traffic control means, such as a signal light or gate. Irrespective of the number of zones in the staging area, and of the size of the staging zones, the traffic in each zone is released successively as the traffic in the zone ahead has cleared its zone. Then, when the entire staging area is clear of traffic, the cycle of events is repeated, first stopping the traffic in the first zone and permitting traffic to accumulate therebehind, then again releasing the first zone of traffic, then again releasing each zone successively. The timing of these events determines the maximum rate of regulated flow of traffic. When traffic flows into the staging area at a rate less than this maximum, the number of vehicles accumulating in each zone will be less than the capacity of the zone. When traffic demand exceeds the maximum rate of regulated flow, all zones will be filled to capacity, a waiting line will develop behind the staging area, and traffic will leave the staging area at the regulated flow rate. Since this rate is always set at a value below the capacity of the roadway, congestion and attendant deterioration of conditions on the roadway during &#39;&#39;&#39;&#39;rush-hour&#39;&#39;&#39;&#39; periods are thereby eliminated. When the staging control is applied to a multilane roadway, events in the staging cycle may be caused to occur at different times in each lane to smooth out traffic flow or for other reasons. Traffic is not permitted to change lanes in the staging areas. It is also particularly useful in merging a greater number of lanes to a lesser number, both on the highway and at bridge or tunnel approaches. It may also be used for assigning a higher priority to a bus or car pool lane over the other lanes of the roadway by delaying the signals of such other lanes. It may also be used as a ramp metering system, with a greater number of zones in the area and with the zones of lesser length, as for even one or two cars. A basic feature of the traffic staging control system is that each car entering the staging area, irrespective of which zone it may be stopped in, makes only one stop in the staging area, and then when released moves on through all other forward staging zones without stopping and thus onto the highway.

[ May 13, 1975 Marmo TRAFFIC STAGING CONTROL SYSTEM [76] Inventor:Anthony B. Marmo, 7916 Coral Blvd., Miramar, Fla. 33023 [22] Filed: May29, 1973 [2]] Appl. No.: 364,436

[52] US. Cl 340/41 R [51] Int. Cl G08g 1/085 [58] Field of Search 340/31R, 35, 36, 40, 41 R [56] References Cited UNITED STATES PATENTS3,241,107 3/1966 Duvivier 340/36 3,302,168 l/l967 Gray et al. 340/31 R3,304,539 2/1967 Auer, Jr. 340/36 3,384,869 5/1968 Waldron 340/363,508,191 4/1970 Barker et al. 340/31 R 3,518,622 6/1970 Barker et al.340/31 R 3,529,284 9/1970 Villemain 340/35 3,593,262 7/1971 Spencer340/36 3,783,446 l/l974 McGimpsey 340/31 R Primary Examiner-Kathleen H.Claffy Assistant Examiner-RandallP. Myers Attorney, Agent, orFirmGustave Miller 57 ABSTRACT This is a system for regulating trafficflow by limiting the number of vehicles that can pass a given point onthe roadway in a given interval of time. Basically, it provides astaging area in the roadway having a plurality of staging zones whereineach zone is provided with a traffic control means, such as a signallight or gate. Irrespective of the number of zones in the staging area,and of the size of the staging zones, the traffic in each zone isreleased successively as the traffic in the zone ahead has cleared itszone. Then, when the entire staging area is clear of traffic, the cycleof events is repeated, first stopping the traffic in the first zone andpermitting traffic to accumulate therebehind, then again releasing thefirst zone of traffic, then again releasing each zone successively.

The timing of these events determines the maximum rate of regulated flowof traffic. When traffic flows into the staging area at a rate less thanthis maximum, the number of vehicles accumulating in each zone will beless than the capacity of the zone. When traffic demand exceeds themaximum rate of regulated flow, all zones will be filled to capacity, awaiting line will develop behind the staging area, and traffic willleave the staging area at the regulated flow rate. Since this rate isalways set at a value below the capacity of the roadway, congestion andattendant deterioration of conditions on the roadway during rush-hourperiods are thereby eliminated.

When the staging control is applied to a multilane roadway, events inthe staging cycle may be caused to occur at different times in each laneto smooth out traffic flow or for other reasons. Traffic is notpermitted to change lanes in the staging areas. It is also particularlyuseful in merging a greater number of lanes to a lesser number, both onthe highway and at bridge or tunnel approaches. It may also be used forassigning a higher priority to a bus or car pool lane over the otherlanes of the roadway by delaying the signals of such other lanes.

It may also be used as a ramp metering system, with a greater number ofzones in the area and with the zones of lesser length, as for even oneor two cars.

A basic feature of the traffic staging control system is.

that each car entering the staging area, irrespective of which zone itmay be stopped in, makes only one stop in the staging area, and thenwhen released moves on through all other forward staging zones withoutstopping and thus onto the highway.

4 Claims, 2 Drawing Figures SEWENCE TABLE l f I /8 20 EVENT TIME STARTSIGNAL CONDITION NUMBER NUMBER INTERVAL TIME RESULTS OF CARS seconds) DC B A RELEASED 1 +5 G G G R Cars collect in O staging zone AB 2 20 G G RG Cars leave zone AB,

' collect in zone BC 3 G R G G Cars leave zone BC, 15

collect in zone CD 30 R G G G Cars leave zone CD, 15

collect behind D 5 +5 G Same as event 1 6 20 G G G Same as event 2 15and so on MENIEBHM 1 3197s 3883.842

TRAFFIC STAGING common D C B A 0 O Q 0 Traffic 0 G O O Signals StagingZone CD 4 Zone BC 4 Zone AB Zones Direction of Traffic Flow ,4 SEQUENCETABLE 4 /a 24 Z EVENT TIME START SIGNAL CONDITION NUMBER NUMBER INTERVALTIME RESULTS OF CARS (seconds) D C B A RELEASED 1 +5 0 G G G R Carscollect in O staging zone AB 2 +5 G G R G Cars leave zone AB, 15

1 collect in zone BC 3 G R G G Cars leave zone BC, 15

collect in zone CD 30 R G G G Cars leave zone CD, 15

collect behind D 5 +5 I G G G R Same as event 1 0 6 20 G G R G Same asevent 2v 15 and so on TRAFFIC STAGING CONTROL SYSTEM BACKGROUND OF THEINVENTION All highways have a limited capacity, that is, they canaccommodate a maximum number of vehicles per mile at some Optimum speed,and when more than that number of vehicles is allowed on the highway, itbecomes congested and traffic slows down or even stops for indeterminateintervals. It is axiomatic that rush-hour traffic is congested and slowbecause the normal capacity of the highway is being exceeded. This makesit desirable to regulate the rate of flow of vehicles entering a sectionof highway. For example, traffic signals have been installed on freewayentrance ramps in several cities to limit the number of vehiclesentering the freeway when it becomes congested. This is called rampmeter ing, and in its simplest form consists of a traffic signal and acontroller which alternates the green and red lights to allow one car ata time to enter the freeway. The maximum metering rate with such acontrol is 720 vehicles per hour. This is discussed on Page 140 ofDesign of Freeway Entrance Ramp and Merging Control Systems, by Buhr,McCasland, Carvell and Drew, pgs. 137-149, Highway Research Record No.279, Highway Research Board, Washington, DC. 1969.

Often a higher rate of regulated flow is needed. At the first downtownentrance to an urban freeway, or on an entrance ramp at an interchangewhere the freeway widens from two to three lanes, the desired flow maybe in excess of 1500 vehicles per hour. This cannot be achieved bymetering one vehicle at a time (720 vph maximum). It has been suggestedthat two or three vehicles be allowed to pass on each green signal toincrease the rate of flow (see Page 141 of above identifiedpublication). The major objection to this form of regulation (one, twoor three vehicles at a time) is that it requires all waiting vehicles tostart and stop each time the lead vehicle enters the freeway. Thiscondition becomes more serious during peak traffic periods when longerwaiting lines develop.

OBJECTS OF THE INVENTION This invention relates to a traffic stagingcontrol system that limits the number of vehicles passing a given pointon the roadway in a given time interval.

This invention has for an object to regulate the traffic on or enteringa highway in such a manner that a maximum desired rate of flow will notbe exceeded.

It is a further object of this invention to achieve such control withminimum inconvenience to vehicle operators.

It is a further object of this invention to provide a traffic stagingarea consisting of a plurality of staging zones for a lane of traffic sothat the traffic in that lane will be limited to a desired maximum rateof flow.

A further object of this invention is to provide a series of trafficstaging zones with a traffic control means at the head end of each zone,as well as at the tail end of the last zone, and to operate the trafficcontrol means so the traffic in each staging zone is released after thetraffic in the zone ahead has cleared that zone.

Yet a further object of this invention is to provide a succession oftraffic staging zones, each capable of holding a desired number of cars,in one embodiment, approximately fifteen average size cars, and thenreleasing the cars in each zone successively after the cars in the zoneahead have cleared the staging area.

A further object of this invention is to provide a traffic controlsystem wherein each car, after entering the staging area, is stoppedonly once before it is permitted to continue on or enter the highway,irrespective of the number of staging zones there are in the stagingarea.

A further object of this invention is to provide a means for safelymerging traffic from a greater to a lesser number of lanes.

A further object of this invention is to provide a means for assigningdifferent priorities to each lane of traffic.

A further object of this invention is to provide an improved trafficcontrol system that is an improvement over that shown in Patents issued,as follows: Waldron, U.S. Pat. No. 3,384,869; Barker et a1, U.S. Pat.No. 3,518,622; Villemain, U.S. Pat. No. 3,529,284; Spencer, U.S. Pat.No. 3,593,262; Barker et a1, U.S. Pat. No. 3,508,191.

DESCRIPTION OF THE FIGURES With the foregoing and other objects in view,as will hereinafter become apparent from the following detaileddescription, when read in conjunction with the accompanying drawing,wherein:

FIG. 1 is a schematic illustration of the staging area of thisinvention.

FIG. 2 is a sequence table showing the timing of the traffic signals andthe movement of vehicles in and out of the staging area during acomplete cycle of events.

DETAILED DESCRIPTION OF THE INVENTION This is a system for regulatingtraffic flow by limiting the number of vehicles that can pass a givenpoint on the roadway in a given interval of time. It provides a stagingarea 10 in which all traffic is controlled by being stopped in one ofthe various staging zones AB, BC or CD of the staging area 10. In thisillustration of this invention, three staging zones AB, BC and CD areprovided in the staging area 10, each zone being intended to hold aboutfifteen cars of average size, in which case, each zone is about threehundred feet in length, and wide enough to hold the maximum car, truckor bus width. Each staging zone has a traffic signal or control havingits conventional timing means, such as a light, A, B and C at its headend, and staging area 10 also has a traffic signal D at its entrance.Only one traffic signal or control is stop or red at one time, while allthe other signals are go or green at the same time.

As shown in the sequence table of FIG. 2, signal A is red in event 1,while signals B, C and D are green, permitting cars to collect instaging zone AB up to the limit of its capacity, and then cars maycollect in successive zones BC and CD, and then behind signal D,depending on the traffic on the highway therebehind. During event 1,that is, the filling of Zone AB, a time interval of 45 seconds ispermitted, this being more than the time it takes cars, of averageacceleration and braking ability, to pass through the entire stagingarea 10 into staging zone AB. Then, signal A turns green, while signal Bturns red, thus commencing event 2, and the cars traffic in zone CD andtherebehind, and signal B turns green, permitting the cars in zone BC toleave onto the highway, traveling through zone AB on their way. Thentwenty-five seconds later, event 4 commences, signal C turns green, andsignal D turns red, for an interval of 5 thirty-seconds, permitting allthe cars in zone CD to leave and go on the highway. Next, event 5commences, signal D turns green, while signal A turns red, and theentire cycle is repeated, as also illustrated in the sequence table ofFIG. 2.

In this sequence table, the above events are illustrated graphically,the first column 12 showing the sequence of events, the second column 14showing the time interval that each particular event occupies, the thirdcolumn 16 showing the starting time in seconds for each event from thebeginning. The fourth column 18 shows the simultaneous signal conditionsfor each event. The fifth column 20 shows the results of the signalconditions of each particular event, while the sixth column 22 shows thenumber of cars released onto the highway during each event, assumingfifteen cars capacity for each zone. The rate of flow is 45 vehicles ineach two-minute interval or 1350 vehicles per hour. This is a maximumrate of flow which results when traffic entering the staging area equalsor exceeds 1350 vehicles per hour. During periods of light traffic, theflow leaving the staging area will equal the flow entering the area, andeach zone will accumulate less than fifteen cars for release to theroadway.

As is obvious from the above description and the sequence table, eachcar is stopped once, and only once, while in the staging area 10, andthereafter each car travels freely without being stopped at all, unlessother cars enter the roadway at a point or points beyond the stagingarea and in numbers sufficient to exceed the capacity of the roadway.

The number of staging zones is optional. Fewer zones would reduce thecost of the installation but increase the total number of vehicle stopsand starts. Notice that most vehicles in zone AB must stop twice beforethey are released to the highway, once behind signal D and once behindsignal A. Vehicles in zones BC and CD stop only once. Thus, with fourtraffic signals, 67 percent of the vehicles are stopped only once.Adding a fifth signal and a fourth staging zone will increase this to 75percent. With six signals and five staging zones 80 percent of thevehicles are stopped only one time. These percentages are correct aslong as traffic entering the staging area is less than or equal to theregulated flow rate. With higher input (or lower regulated flow) awaiting line will develop, and vehicles in that line may be stopped onceor twice before they reach a staging zone.

The time intervals and/or the number of events may be set up differentlyfrom that above, depending on the rate of flow desired and thecharacteristics of the roadway and the vehicles.

When there are several lanes, the events of the staging zones in onelane may be out of phase with the events of the corresponding stagingzones of the other lanes, so that the cars will leave onto the highwayfrom one lane while the cars in another lane may be stopped, or startingto leave at a different interval, thus smoothing out the traffic flow onthe highway beyond the staging areas.

At a bridge or tunnel approach, staging areas serve for merging trafficfrom adjacent zones by phasing the For example, if ten signals areinstalled with only one car length between each of them, during event 1(first signal red, all others green) ten cars will move into the stagingarea. During event 2 (second signal red, all others green), the firstcar will be released; during event 3 the second car will be released,and so on. If event 1 takes 40 seconds, and events 2 through 10 take 5seconds each, total elapsed time for a complete staging cycle isseconds. During that time, nine cars have been released for a flow rateof about 380 vehicles per hour.

When events 2 through 10 have the same time intervals, the rate of flowis fixed and determined by that time interval. In the example above, atime interval of 10 seconds would reduce flow to about 250 vph.

On some freeways, traffic control computers regulate the entrance rampflow in response to conditions on the freeway. The flow rate from theentrance ramp is variable, each car on the ramp being released when thecomputer determines that there will be room for it on the freeway (seeWaldron U.S. Pat. No. 3,384,869; Barker U.S. Pat. No. 3,518,622 andBarker U.S. Pat. No. 3,508,191). It is obvious that this computer canalso release each staging zone, in succession, to achieve the samevariable flow.

Staging controls should be used on all high-volume freeway entranceramps instead of conventional ramp metering devices. Staging controlsmay also be installed on exit ramps (and on all lanes at the end of afreeway) to store peak-hour traffic and then discharge it at a rate thatsurface roads can handle.

Full control of a freeway can be achieved with staging controlsinstalled on all freeway lanes (at one or more critical locations) andmetering devices or staging controls on selected entrance and exitramps. On some freeways, it may be desirable to control each lane at adifferent rate of flow. Less traffic in the curb lane can improvemerging from entrance ramps, and the inside lane can generallyaccommodate a higher rate of flow. Such lane-to-lane variations inregulated flow can be achieved with all traffic signals operating in thesame time sequence (if the length of staging zones is different for eachlane) or with the same length staging zones (if the signal timing isvaried for each lane). No lane changing is permitted in the stagingarea. Staging controls can also be set to give higher priority to one ormore lanes, such as for buses or car pools, to allow these vehicles morerapid access to a freeway, tunnel or bridge than the rest of thetraffic.

The Traffic Staging Control can also provide safe and efficient mergingwhen one or more lanes on a highway are terminated. This is especiallyimportant during peak traffic periods when, for example, three congestedlanes cannot safely be merged into two. The staging control, however,can stop all traffic on the three congested lanes, and then release itat a rate that does not exceed the capacity of the two available lanes.

Among the advantages of the Traffic Staging Control System is that itprovides a steady regulated flow of traffic, even at high flow rates. Itminimizes stop-and-go driving for vehicles in the waiting line. It canbe constructed from standard traffic signal and control components. Itcan be used as a merge control for highway or city traffic.

ABSTRACT OF DRAWING In the drawing, like reference numerals in the twofigures refer to like parts for the purposes of explication, andmarshalled below are the reference numerals of this improved TrafficStaging Control System:

traffic staging area l2 column of events 14 column of time intervals inarea 16 starting time column 18 signal conditions column 20 resultscolumn 22 column of cars released A traffic signal at end of zone AB ABzone between A and B B traffic signal at end of zone BC BC zone betweenB and C C signal at end of zone CD CD zone between BC and D D signal atentrance of staging area 10 consisting of a plurality of' successivecontiguous staging zones of predetermined average vehicle capacity, aplurality of spaced uni-directional stop and go traffic signals on saidstaging area, the size of each staging zone being determined by thespacing of the traffic signals, one signal being at the entrance to saidstaging area and one signal being at the exit end of each staging zone,said traffic signals being coordinated to provide a stop indication atonly one signal at a time while simultaneou sly providing a goindication at each other signal, the stop indication progressingsuccessively from the foremost signal at prescribed intervals to thenext rearward signal, and then, at a prescribed time interval, the cycleis repeated indefinitely.

2. The uni-directional traffic control system of claim 1, there being aseparate staging area for each traffic lane of a multiple lane highway,the traffic indications of each lane being coordinated in staggaredrelation to each other lane, wherey the traffic release in each lane isout of phase with the traffic release of each of the other lanes.

3. The uni-directional traffic control system of claim 2, said trafficindications being coordinated to alternate the release of traffic from agreater number of lanes to a lesser number of lanes to thereby safelymerge the traffic from a greater number of lanes into a lesser number oflanes.

4. The uni-directional traffic control system of claim 1, there being aseparate staging area for each traffic lane of a multiple lane highway,the traffic indications of each lane being coordinated to providepriority in one or more lanes of the highway and to release traffic inthe non-priority lanes at a lower rate than in the one or more prioritylanes.

1. A uni-directional traffic control system for limiting the flow oftraffic on a uni-directional highway to a desired maximum rate of flowcomprising a staging area consisting of a plurality of successivecontiguous staging zones of predetermined average vehicle capacity, aplurality of spaced uni-directional stop and go traffic signals on saidstaging area, the size of each staging zone being determined by thespacing of the traffic signals, one signal being at the entrance to saidstaging area and one signal being at the exit end of each staging zone,said traffic signals being coordinated to provide a stop indication atonly one signal at a time while simultaneously providing a go indicationat each other signal, the stop indication progressing successively fromthe foremost signal at prescribed intervals to the next rearward signal,and then, at a prescribed time interval, the cycle is repeatedindefinitely.
 2. The uni-directional traffic control system of claim 1,there being a separate staging area for each traffic lane of a multiplelane highway, the traffic indications of each lane being coordinated instaggared relation to each other lane, wherey the traffic release ineach lane is out of phase with the traffic release of each of the otherlanes.
 3. The uni-directional traffic control system of claim 2, saidtraffic indications being coordinated to alternate the release oftraffic from a greater number of lanes to a lesser number of lanes tothereby safely merge the traffic from a greater number of lanes into alesser number of lanes.
 4. The uni-directional traffic control system ofclaim 1, there being a separate staging area for each traffic lane of amultiple lane highway, the traffic indications of each lane beingcoordinated to provide priority in one or more lanes of the highway andto release traffic in the non-priority lanes at a lower rate than in theone or more priority lanes.